Yankee dryer



YANKEE DRYER 4 Sheets-Sheet l On mm Oct. 30, 1962 H. M. OSTERTAG Filed March 14, 1958 N INVENTOR HARRY/1d. OSTERTAQ DECEASEfi B7 law/my M, osrmm museum/e O47ATTORNEY Oct. 30, 1962 H. M. OSTERTAG 3,060,592

YANKEE DRYER Filed March 14, 1958 4 Sheets-Sheet 2 INVENTOR.

HAAK Y M OSTERMG, DECEASED 8y HARRY 04. OSTERTAG, R.,XECU7'0R ATTORNEY Oct. 30, 1962 H. M. OSTERTAG 3,060,592

YANKEE DRYER Filed March 14, 1958 4 Sheets-Sheet 3 FIG. 4

, INVENTOR.

35 HARRY M- asmqma, ozczAu-p fir HARRY M. 0575RPM, .m Hal/ran T Q EYW Oct. 30, 1962 H. M. OSTERTAG YANKEE DRYER 4 Sheets-Sheet 4 Filed March 14, 1958 FIG. 6.

. INVENTOR. many 44- as meme ptcustd 5r mum r M as rein 0,, :xscurm .WATIQRNEY United rates Fatent 3,060,592 YANKEE DRYER Harry M. Ostertag, deceased, late of Straftord, Pa., by Harry M. Ostertag, Jr., executor, 57 Rosedale Ave, Strafiord, Wayne P.O., Pa.

Filed Mar. 14, 1958, Ser. No. 721,428 11 Claims. (Cl. 34-124) The present invention relates to paper manufacturing machinery and more particularly to structural improvements in drying cylinders of the Yankee type.

Integration of the Yankee dryer into a system for the continuous manufacture of paper necessitates the availability of a rotatable drying cylinder capable of perform ing its function both efficiently and safely in less than one full revolution thereof with respect to each incremental length of the paper Web. Since at this stage of the manufacturing process the moisture content of the paper Web must be very substantially reduced, the steam internally supplied to the cylinder for removal of this moisture by vaporization must be of very high temperature, entailing correspondingly high pressure values due to the direct relationship between temperature and pressure in a confined space. The structural demands upon the cylinder for the safe handling of such high temperatures and pressures are in general conflict with the design requirements oriented toward efficient heat transfer through the external urface of the cylinder, and current trends toward ever-higher operational speeds and evergreater dimensional capacities, doing their part in rendering present structures inadequate, correspondingly make more critical these and other interrelated and often opposing factors, further aggravating the complexities involved in providing an optimum drying cylinder structure. Existing structures, both of single and double shell varieties, under safe operating conditions constitute a limitation on the extent of the advantages to be realized from higher operational speeds and steam pressures, While at-. tempts to utilize such equipment at the higher speeds and pressures currently in vogue are responsible for the creation of markedly hazardous conditions in the industry. It is a principal objective of this invention to provide a drying cylinder capable of sustained and efiicient operation at maximum speed and pressure while greatly reducing the hazards inherent in such operation.

A further objective of the invention is to provide a structure applicable particularly to the double shell type of dryer and suitable for use not only where inner and outer shells utilize the same materials but also where different materials with differing thermal coeflicients, tensile and compressive strengths, etc., are required.

Another objective of this invention is the provision of a cylinder structure capable of safe operation with steam pressures up to 160 pounds per square inch, the maximum presently allowable for untired pressure vessels by the American Society of Mechanical Engineers Code On Unfired Pressure Vessels as adopted by the Insurance Underwriters' Still another important objective is the provision of a drying cylinder structure having built-in flexibility adequate for safe and efficient operation with simultaneous handling of the larger differential thermal and mechanical stresses inherent in the use of larger cylinders, both in diameter and in face length, combinations of steel and cast iron or other combinations of materials in the same cylinder, increased operational speeds and consequent higher steam temperatures and pressures, all or severally together with minimum thickness of external shell for efficiency of heat, transfer, and adaptable for use with efiicient means for supply of live steam and removal of condensate and exhaust steam.

Still a further advantage of the invention is simplification of structure to facilitate fabrication of component parts, assembly, installation, and maintenance, with accompanying elimination of points and areas of stress concentrations and other relatively weak structural features.

Dryer structures must necessarily be made wider than the width of the paper Web being dried thereby. The paper has a cooling eifect on the surface it covers which is absent from the ends of the surface not covered by the paper, the differential thermal stresses at the edge of the paper and beyond being consequently high and critical. Cylinders expand to a greater amount at their ends than where covered by the paper and are often dubbed or reduced in diameter outside of the paper line to prevent excessive pressure against the dryer by the creping doctors in such areas. Existing structures generally use supporting spokes which double as steam inlet pipes, as in double shell dryers, or are immersed in the steam, as in single shell dryers, being thereby heated to the prevailing steam temperature and expanding to force the ends of the shell out radially, further aggravating the undesirable end condition. The large end heads in single shell dryers, being similarly heated in operation, contribute an addi tional undesirable radially expansive force of considerable amount. It is more particularly a principal objective of the present invention to provide an improved double shell dryer structure minimizing the foregoing critically stressed end condition.

The foregoing, together with additional objectives, purposes and advantages of the present invention, will become more apparent from the following detailed description, referring to the accompanying drawings in which:

FIGURE 1 is a longitudinal cross-sectional view of a double shell dryer made in accordance with the present invention, taken along line 11 of FIGURE 2;

FIGURE 2 is a transverse cross-sectional view of the dryer of FIGURE 1, taken along line 2-2 of FIGURE 1;

FIGURE 3 is an elevational view of the steam inlet end of the dryer of FIGURE 1, showing spoke assemblies between the inner shell and the center shaft, and the flexible head assembly between the outer shell and the inner shell;

FIGURE 4 is an enlarged detail cross-sectional view of the flexible head assembly connecting the outer and inner shells of the dryer as shown in FIGURE 1;

FIGURE 5 is an enlarged detail cross-sectional view of a modified form of flexible head assembly connecting the outer and inner shells of the dryer; and

FIGURE 6 is an enlarged fragmentary detail crosssectional view of one of the steam inlet pipe assemblies in the dryer of FIGURE 1.

The features and advantages of the present invention are most clearly reflected in an embodiment thereof as shown in the accompanying figures which illustrate a Yankee dryer of the double shell type, the inner shell 10 being made preferably of steel for necessary structural strength and toughness, and the outer shell 11 being made preferably of cast iron to provide an external surface suitable for creping papers for instance. The invention however equally contemplates that the inner and outer shells may be made of any desired materials, either the same or different, its advantages being realizable with any selected combination thereof. In the illustrated embodiment the inner shell 10 and the outer shell 11 are assembled concentrically with the center shaft 12. Inner shell 10 is connected to and supported from the center shaft 12 by means of spokes 13, and outer shell 11 is in turn connected to and supported from inner shell by means of flexible head assemblies 14. Center shaft 12 is hollow, providing a chamber 15 for live steam introduced through hollow shaft journal 16, such steam being uniformly distributed from chamber 15 in center shaft 12 into the annular space 17 between inner shell 10 and outer shell 11 by means of steam pipes 18 which are spaced selectively about and along and connected to ports in center shaft 12, extending radially outward therefrom through inner shell 10 and into annular space 17. Provision may be made for removal of condensate and exhaust steam from annular space 17 through conduits (not shown) connecting openings 2 in inner shell 10 and openings 21 in center shaft 12 into exhaust chamber 22 in center shaft 12, separated from live steam chamber 15 by means of baffle 23, and finally from chamber 22 through hollow shaft journal 24.

The flexible head assemblies 14, referred to above and having the dual purpose of steam containment and structural support, are shown generally in FIGURE 1 and more particularly in the enlarged detail view of FIGURE 4. Each assembly, for each end of the dryer cylinder, includes a flexible head member 30' comprising a relatively thin bow shaped ring terminating at its inner and outer edges in integrated flanged inner and outer clamping rings 31 and 32 respectively, said bow shaped ring and clamping rings preferably being machined out of one piece of material. Recesses 31a and 31b in inner clamping ring 31 and recesses 32a and 32b in outer clamping ring 32 are provided for improved flexibility and to avoid any areas of abrupt contour change which would cause local stress concentrations. Assembly of flexible head assembly 14 to outer shell 11 is accomplished by bolts 33 extending through outer clamping ring 32, inwardly disposed flange 34 forming an integral part of outer shell 11 and segmental bolting ring 35, while assembly to inner shell 10 may be accomplished by bolting inner clamping ring 31 directly to the inner shell by means of bolts 36.

Spokes 13, connecting inner shell 10 to center shaft 12 as referred to above, are shown in FIGURE 1 to comprise three axial groupings, one located centrally of the cylinder for intermediate support and one each at the ends of the cylinder. The necessity for the centrally located grouping or for additional intermediate groupings depends on the length of the cylinder, etc. Use of this intermediate support spoke system will permit reduction in diameter of center shaft and inner shell thickness in a dryer of any substantial length. As shown in FIGURE 3,

each spoke grouping preferably includes an uneven number of spokes 13 uniformly spaced circumferentially so that no two of them are exactly opposite diametrically. Spokes 13 are of solid generally flat cross-section and have irregular lengthwise contour to permit of radial expansion thereof in operation while minimizing the stresses consequent thereon. The preferred mounting for spokes 13, as shown in FIGURES l and 3, includes inner and outer flanged rings 50 and 51 welded to the respective ends of each spoke, said rings being machined and in turn bolted by means of bolts 52 to mating flanges 53 and 54 which are welded to the center shaft 12 and inner shell 10 respectively, flanges 53 being integrated with journals 16 and 24 for the end spoke assemblies as shown in FIGURE 1. Alternatively the spokes may be welded directly to the center shaft or journals and inner shell without the intervention of flanges 50, 51, 53 and 54. The preferred mounting however will permit simplified and more accurate assembly.

Steam pipes 18 through which live steam is uniformly supplied to annular space 17 from chamber 15 as aforementioned are shown in FIGURES l and 2 to comprise radial groupings spaced axially of the cylinder as needed for optimum distribution to the interior of the drying surface provided by the outer shell 11. FIGURE 6 shows further details of each pipe and its assembly to the structure. Each pipe is a straight radially extending hollow tube bolted at its inner end to the center shaft 12 by means of flanged mating connections 60 and 61 so as to mate with a port opening in the center shaft and not protrude within the chamber 15. Each pipe may be made in two sections and connected by intermediate flange coupling 18a to simplify assembly. The outer end of each pipe extends through inner shell 10 through conventional packing gland assembly 62 and protrudes substantially into annular space 17, terminating very close to the inner surface of outer shell 11. The end of each pipe extending into annular space 17 is provided with chosen numbers of apertures 63 of desired diameters and spacings, the illustrated embodiment showing fourteen such apertures 63 in each pipe spaced radially and circumferentially in staggered relationship, the pipes being distributed throughout the annular space 17 between the inner and outer shells for best uniformity of steam distribution and avoidance of concentrated hot spots. The aforesaid flexible or floater mounting of each pipe with respect to the inner shell permits radial expansion of the pipes through their respective packing glands 62 in operation with increased temperature, without accompanying distortions and stress risers.

In assembling the dryer, outer shell 11 is placed over inner shell 10 before installation within the annular space 17 of such condensate collector means as may be selected. Outer shell centering bolts 70 are assembled through packing glands 71 at the ends of inner shell 10 and are adjusted so as to hold outer shell 11 in centered position. The condensate collector means may then be installed, after which flexible head assemblies 14 are installed, following which centering bolts 70 are backed off from contact with the outer shell.

A modified form of flexible head assembly 80, which may be used in place of flexible head assembly 14, is shown in the enlarged detail view of FIGURE 5. Here the flexible head member includes a laminated spring group comprising a series of continuous flexible rings 81, three in number in the illustrated embodiment, together with a series of alternately discontinuous flexible rings, six in number in the illustrated embodiment, made up of segments 81a and 81b. Numbers and arrangements of such rings and segments may of course be varied to meet particular design requirements for needed flexibility, etc. Attachment of this laminated spring group to the outer shell is accomplished by means of bolts 82 extending through outer clamping ring 83, then through the outer portion of the laminated spring group, then through gasket 84 and inwardly disposed flange 85 forming an integral part of outer shell 11, and segmental bolting ring 86. Similarly, attachment to the inner shell is accomplished by means of bolts 87 extending through the inner clamping ring 88, then through the inner portion of the laminated spring group, gasket 89 and internally threaded flange 90 extending outwardly from and welded to inner shell 10. In the illustrated embodiment the face to face dimension of flange 90 is preferably less than the face to face dimension of flange 85, each laminated spring group thereby being assembled in a pre-stressed condition such that in operation the axial expansion of the center shaft 12 and inner steel shell 10, being greater than that of the outer cast iron shell 11 due to temperature differential as well as different thermal coefficients, will return the spring groups to a position of little or no axial deflection. The amount of pre-stressing will vary with the length of face of the dryer cylinder, etc.

In operation of the structure described and illustrated hereinabove, the flexible head assemblies, constituting flexible supporting connections between the inner and outer shells, provide compensation for difference in expansion both axially and radially between the inner and outer shells while providing adequate strength both for containment of the relatively low volume of steam and structural support of the outer shell, at the same time effectivelly insulating the structure from undesirable stress risers which would result from such differential expansion in more rigidly constructued structures. The spokes supporting the inner shell from the shaft, being relieved of the double duty of steam transmission and being substantially out of contact with the steam are generally in tension due to the cooling effect of the surrounding air, thereby avoiding any contribution to the radially expansive forces in the shells and cooperating with the flexible head assemblies in their effectiveness in minimizing any dilferential stress condition. The steam supply pipes similarly cooperate in achieving this effectiveness, being relieved of any structural support duty and made free to expand independently of the shells through their floating connections through the inner shell, thereby avoiding imposing any force upon either shell. The generally flat cross-section of the supporting spokes, made possible by divorcing of the steam supply means therefrom, provides an added measure of flexibility to compensate for any different-a1 axial expansion between the center shaft and the inner shell, contributing further to the effectiveness of the overall structure in achieving its designated objectives.

While the invention has now been described and illustrated in considerable detail, it is not intended to be confined to the particular embodiments and arrangements thereof so shown. Many modifications and variations in such embodiments and arrangements, as well as other embodiments thereof, will occur to those skilled in the art from a reading of this specification, all of which must be understood to be fully within the scope and coverage of this invention and the appended claims.

Having so described and illustrated my invention, I claim:

1. A Yankee dryer having a hollow center shaft containing a live steam chamber, an inner cylindrical shell of substantially greater diameter than said shaft concentrically assembled over the shaft and a plurality of solid generally flat cross-sectioned supporting spokes joining said inner shell to said shaft, an outer cylindrical shell of selectively greater diameter than said inner shell concentrically assembled over said inner shell and flexible head assemblies structurally connecting the ends of said outer and inner shells together and enclosing an annular space for steam between said outer and inner shells, a plurality of steam pipes selectively distributed axially and radially of the dryer and extending from said center shaft live steam chamber into said annular space, and a packing gland assembly floating connection between each steam pipe and the inner shell.

2. In a Yankee dryer having a hollow center shaft, a coaxial inner shell, and a coaxial outer shell, and an annular space between said inner and outer shells, a plurality of steam pipes extending from said center shaft through said inner shell into said annular space, and a floating connection between each steam pipe and the inner shell.

3. In the Yankee dryer of claim 2, each of said steam pipes terminating near the inner surface of the outer shell, and the portion of each such pipe within said annular space being provided with a plurality of apertures spaced radially and circumferentially in staggered relationship thereabout.

4. A drying cylinder having a hollow center shaft terminating in journals for the rotatable mounting thereof, a coaxial inner shell, and a coaxial outer shell, a spoke assembly connecting said inner shell to said center shaft, a flexible head assembly connecting said outer shell to said inner shell and defining therewith an enclosed annular space, and means for introducing steam into the shaft and passing it from the shaft into said annular space, said flexible head assembly including a relatively thin bow-shaped ring.

5. A drying cylinder having a hollow center shaft terminating in journals for the rotatable mounting thereof, a coaxial inner shell, and a coaxial outer shell, a spoke assembly connecting said inner shell to said center shaft, a flexible head assembly connecting said outer shell to said inner shell and defining therewith an enclosed aunular space, and means for introducing steam into the shaft and passing it from the shaft into said annular space, said flexible head assembly comprising an inner clamping ring, an outer clamping ring, and a bow-shaped joining said inner and outer clamping rings.

6. A drying cylinder having a hollow center shaft terminating in journals for the rotatable mounting thereof, a coaxial inner shell, and a coaxial outer shell, a spoke assembly connecting said inner shell to said center shaft, a flexible head assembly connecting said outer shell to said inner shell and defining therewith an enclosed annular space, and means for introducing steam into the shaft and passing it from the shaft into said annular space, said flexible head assembly comprising an inner clamping ring, an outer clamping ring, and a bow-shaped ring joining said inner and outer clamping rings, said bow-shaped ring being integral with said clamping rings, and at least one such clamping ring having at least one recess at the juncture thereof with said bow-shaped ring.

7. A drying cylinder having a hollow center shaft terminating in journals for the rotatable mounting thereof, a coaxial inner shell, and a coaxial outer shell, a spoke assembly connecting said inner shell to said center shaft, a flexible head assembly connecting said outer shell to said inner shell and defining therewith an enclosed annular space, and means for introducing steam into the shaft and passing it from the shaft into said annular space, said flexible head assembly comprising a unitary relatively thin bow shaped ring terminating at its inner and outer edges in integrated flanged inner and outer clamping rings.

8. In a Yankee dryer having a hollow center shaft terminating in journals for the rotatable mounting thereof, a coaxial inner shell, a coaxial outer shell, and head assemblies joining said inner and outer shells and defining therewith an enclosed annular space, a plurality of solid generally flat cross-sectioned supporting spokes with irregular lengthwise contour joining said inner shell to said shaft, a plurality of ports in said center shaft, a hollow steam pipe connected to each of said ports and extending therefrom through said inner shell into said annular space, and a fluid tight floating connection between said pipe and said inner shell.

9. In a Yankee dryer having a hollow center shaft terminating in journals for the rotatable mounting thereof, a coaxial inner shell, a coaxial outer shell, and head assemblies joining said inner and outer shells and defining therewith an enclosed annular space, a plurality of ports in said center shaft, a hollow steam pipe connected to each of said ports and extending therefrom through said inner shell into said annular space, and a fluid tight floating connection between said pipe and said inner shell.

10. A drying cylinder having a hollow center shaft terminating in journals for the rotatable mounting thereof, a coaxial inner shell, and a coaxial outer shell, a spoke assembly connecting said inner shell to said center shaft, a flexible head assembly connecting said outer shell to said inner shell and defining therewith an enclosed annular space, and means for introducing steam into the shaft and passing it from the shaft into said annular space, said flexible head assembly comprising a unitary relatively thin bow shaped ring terminating at its inner and outer edges in integrated flanged inner and outer clamping rings, the junctures of said bow shaped ring with said clamping rings being recessed to eliminate abrupt contour changes.

11. A drying cylinder having a hollow center shaft terminating in journals for the rotatable mounting thereof, an inner shell coaxially assembled over said shaft and a plurality of supporting spokes joining said inner shell to said shaft, an outer shell coaxially assembled over said inner shell and flexible head assemblies structurally connecting the ends of said outer shell and said inner shell together and enclosing an annular space between said outer and inner shells, and means for introducing steam into the shaft and passing it from the shaft into said annular space, each flexible head assembly comprising an inner clamping ring fastened to said inner shell, an outer clamping ring fastened to said outer shell, and a relatively thin bow-shaped ring with its concavity presenting toward said annular space joining said inner end and outer clamping rings.

References Cited in the file of this patent UNITED STATES PATENTS Ostertag et al. Aug. 7, 1951 Hinnekins Mar. 9, 1954 Ohlson et al May 11, 1954 Schadler Aug. 3, 1954 White et al Nov. 29, 1955 Hornbostel Dec. 31, 1957 Coudriet June 10, 1958 FOREIGN PATENTS France Apr. 6, 1955 

